The presence of pili on certain organisms was noted many years ago and the first isolation of such material was reported in 1959 by Brinton in Nature 183, 782-786. Since that time many piliated organisms have been identified. Among these may be mentioned:
Neisseria gonorrhoeae PA0 Escherichia coli PA0 Pseudomonas aeruginosa PA0 Neisseria meningitidis, lactamica PA0 Proteus vulgaris PA0 Moraxella species PA0 Vibrio cholerae PA0 Salmonella species PA0 Bordatella pertussis PA0 Falvobacterium species PA0 Klebsiella species PA0 Serratia species PA0 Enterobacter species PA0 Corynebacterium diphtheriae PA0 Corynebacterium renale PA0 Actineobacter species PA0 Flavobacterium species PA0 Aeromonas species PA0 Shigella flexneri
The pili of these various organisms may be separated from the cells and from cell debris and provide pilic material which, when injected into an immune-responsive system, will cause the formation of antibodies to said pilic material.
Heretofore, the immunological relationship of members of a particular group of immunologically cross-reactive piliated organisms has been unclear. There have been reasons to suppose that the existence of a common antigenic factor as well as the existence of individual determinants or groups of determinants specific to each particular strain. Heretofore, the nature of this relationship has not been specified.